JP6567042B2 - Method for the synthesis of stabilized chlorotrifluoroethylene polymers and products produced using such polymers - Google Patents

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is hereby incorporated by reference in US Provisional Patent Application No. 62 / 045,746, filed Sep. 4, 2014 (Title: Method for Synthesizing Stabilized Chlorotrifluoroethylene Polymers, and Claiming the benefit of the priority of products made with polymers), the entire contents of which are hereby incorporated by reference.

TECHNICAL FIELD The present disclosure relates generally to the synthesis of stabilized chlorotrifluoroethylene (CTFE) polymers and products made using such polymers. More specifically, the present disclosure provides for the stabilization of stabilized CTFE polymers (eg, CTFE homopolymers (PCTFE) and CTFE copolymers, etc.) to reduce their acidity and improve their thermal stability. The present invention relates to synthesis using an agent, and a product (for example, a packaging film) manufactured using such a polymer.

  In this field, the preparation of PCTFE and PCTFE-based copolymers are well known. Examples of such copolymers include CTFE-vinylidene fluoride copolymer, CTFE-tetrafluoroethylene copolymer, and CTFE-ethylene copolymer. Examples include, but are not limited to, polymers. Such materials are described in detail, for example, in ENCYCLOPEDIA OF POLYMER SCIENCE AND ENGINEERING, 2nd edition, volume 3, page 463 (published by John Wiley and Sons). As described therein, articles and films made of PCTFE materials are non-flammable, resistant to chemicals and strong oxidants, and exhibit desirable moisture barrier properties.

  Various processes suitable for the formation of CTFE-based polymers are currently known. High molecular weight CTFE homopolymers and copolymers can be prepared by free radical initiated bulk polymerization, suspension polymerization, or aqueous emulsion polymerization using a suitable initiator system, or ionized irradiation. Can also be done.

  In the case of PCTFE formed by an aqueous suspension polymerization process, an iron salt, copper salt or silver salt is used under acidic conditions (pH 2 or less) as a catalyst together with a redox initiator (eg, alkali metal persulfate and bisulfite). PCTFE polymers produced by this method are acidic and have low thermal stability when processed at temperatures of about 275 ° C to about 325 ° C. This low thermal stability results from the polymer being sealed at one or both ends by an inorganic moiety derived from the initiator species. Such ionic end groups may be hydrolyzed during work-up to produce unsaturated olefins and carboxylic acids. Therefore, plaques prepared by thermal compression from PCTFE samples produced by the above method often exhibit undesirable bubbles and discoloration, which is at the end of the polymerization when the reaction reaches high conversion. This is thought to be due to the low molecular weight oligomers produced. The acidic PCTFE polymer extracts the metal from the reactor and forms a metal salt during finishing. Sealing the inorganic portion results in a relatively high residual ash content of the PCTFE resin produced, thereby limiting the application range of articles formed using the PCTFE polymer resin. Such polymeric materials are known to have low dielectric strength and are often undesirable for use in electrical and electronic devices and / or packaging materials.

  In the case of a PCTFE polymer produced by an emulsion polymerization method, a surfactant is required to form a stable emulsion. Most surfactants are fluorinated compounds with polar head groups, and removal of this surfactant is an important part of the finishing process. Depending on the degree of adsorption to the polymer particles, it is often very difficult to completely remove the surfactant. More recent studies have shown that such surfactants are bioaccumulative, toxic and environmentally sustainable.

  Regardless of the method used, the PCTFE homopolymer has a strong tendency to crystallize, so that the physical properties, mechanical properties, electrical properties, and barrier properties are optimally maintained by keeping the molecular weight high and maintaining the crystallinity. It is. For many end uses, it is necessary to reduce the acidity of the polymer and to suppress degradation of the polymer during processing. This can be achieved by neutralizing the PCTFE polymer with a suitable neutralizing agent (buffer solution, aqueous base solution, etc.).

  Accordingly, as will be apparent to those skilled in the art, improved PCTFE homopolymers and copolymers are now and in the future suitable for manufacturing articles by processing at high temperatures or suitable for inclusion in shaped member structures. Is necessary. There is also a continuing need in the art to produce thermally stable and neutral PCTFE homopolymers and copolymers with improved machinability, especially with regard to melt extrusion, pelletization, thermoforming, and laminating. It is. Furthermore, other desirable features and characteristics of the present inventive subject matter will become apparent from the following detailed description of the inventive subject matter and the appended claims, taken in conjunction with the accompanying drawings and this disclosure. Let's go.

  Disclosed herein are methods for synthesizing stabilized chlorotrifluoroethylene polymers, and products made using such polymers. In one exemplary embodiment, a method for synthesizing a chlorotrifluoroethylene (CTFE) -based polymer comprises one or more units comprising CTFE in a reaction medium having a pH of about 1.5 to about 2.5 in the presence of an initiator. Reacting the monomer and after a predetermined polymerization reaction time has elapsed, adding a neutralizing agent to the reaction medium to raise the pH of the reaction medium within the range of about 1.8 to about 6.0.

  This summary briefly introduces the selection of concepts that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used in an auxiliary manner in defining the scope of the claimed subject matter.

  Hereinafter, the present disclosure will be described in conjunction with the following drawings, in which like reference numerals denote like components.

FIG. 1 is a plot of temperature and pressure in a reaction vessel versus time during the synthesis of a CTFE polymer according to the prior art. FIG. 2 is a plot of temperature and pressure in a reaction vessel versus time during the synthesis of a CTFE polymer according to various aspects of the present disclosure. FIG. 3 is a plot of temperature and pressure in a reaction vessel versus time during the synthesis of a CTFE polymer according to various aspects of the present disclosure. FIG. 4 is a plot of temperature and pressure in the reaction vessel versus time during the synthesis of a CTFE polymer according to various aspects of the present disclosure. FIG. 5 is a plot of temperature and pressure in a reaction vessel versus time during the synthesis of a CTFE polymer according to various aspects of the present disclosure. FIG. 6 is a plot of temperature and pressure in a reaction vessel versus time during the synthesis of a CTFE polymer according to various aspects of the present disclosure. FIG. 7 is a plot of the results of thermogravimetric analysis of the polymer produced by the synthesis method shown in FIGS. FIG. 8 is a plot of temperature and pressure in the reaction vessel versus time during the synthesis of a CTFE polymer according to a further aspect of the present disclosure. FIG. 9 is a plot of temperature and pressure in the reaction vessel versus time during the synthesis of a CTFE polymer according to a further aspect of the present disclosure.

  The following detailed description is exemplary only and is not intended to limit the invention or the application and uses of the invention. As used herein, the term “exemplary” means “serving as an example, instance, or illustration”. Thus, any aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects. All embodiments described herein are exemplary embodiments provided to enable one of ordinary skill in the art to practice and are not intended to limit the scope of the invention as defined in the claims. Furthermore, the above aspects are not bound by any obvious or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.

  The present disclosure provides a method for synthesizing stabilized CTFE polymers (eg, PCTFE and CTFE copolymers, etc.) using neutralizing agents that reduce their acidity and improve their thermal stability, and so on. The product (for example, packaging film etc.) manufactured using the right polymer is provided. In some embodiments, the neutralizing agent may be provided as an aqueous base solution, and in other embodiments, the neutralizing agent may be provided as a buffer.

  In some embodiments using an aqueous base neutralizer, the polymer is neutralized with a sodium hydroxide solution or a potassium hydroxide solution. Such a solution is added to the reaction medium for neutralization, but the pH of the reaction medium is maintained in the neutral or slightly lower acidic region (less than 7) and the polymer formed in the reaction medium is transparent. The amount is carefully controlled in order to preserve the properties (as described above, the addition of a slight excess of base raises the pH to the alkaline region (above 7) and the color of the PCTFE polymer changes from yellow to brown). . Accordingly, in these embodiments, it is preferred to control the pH to about 3 to about 7 to minimize undesirable color development in the polymer.

  However, in a more preferred embodiment, a buffer is used as a neutralizing agent to maintain a controlled pH. The term “buffer” as used herein refers to an aqueous solution comprising a mixture of a weak acid and its conjugate base, or a mixture of a weak base and its conjugate acid. The buffer is resistant to pH changes due to the presence of equilibrium between its components. The buffer may be acidic or basic and a useful pH range can be selected. Preferred buffers that can be used to practice the embodiments described herein include acidic buffers having a pH of about 3.0 to about 7.0. Suitable acidic buffers include acetic acid, citric acid, lactic acid, and phosphate buffer.

  In addition to the desired pH range, the buffer chosen is preferably water soluble and can be removed after neutralization. Among the acidic buffers exemplified above, the acetic acid buffer and the lactic acid buffer are relatively higher in water solubility than the citrate buffer and the phosphate buffer. In view of solubility and pH range, a lactic acid buffer and an acetic acid buffer are preferred, and a lactic acid buffer is most preferred for use in the implementation of the embodiments described herein. Lactic acid based buffers have a useful pH range of about 4.0 to about 6.0 and include lactic acid and lactate (eg, sodium, potassium, and / or ammonium salts, etc.). Among the lactic acid buffers, ammonium lactate is particularly preferable because of its solubility and free of metal ions. Ammonium lactate is commercially available in various concentrations from Univar Inc. of Downers Grover, Illinois, USA and is stable at ambient conditions. The 65% by weight aqueous ammonium lactate solution has a pH of about 4.8. It is also possible to wash off the ammonium lactate buffer with water after completing neutralization with the ammonium lactate buffer in the CTFE polymer reaction medium.

  The addition of the ammonium lactate solution neutralizes the reaction medium from an acidic pH to a near neutral pH (eg, about 1.8 to about 6.0, specifically about 1.8 to about 5.0). , More preferably about 3.0 to about 5.0, most preferably about 4.0 to about 5.0). A preferred ammonium lactate buffer concentration is from about 5% to about 75% by weight in aqueous solution. A more preferred ammonium lactate buffer concentration is about 20% to about 65% by weight, and a most preferred ammonium lactate buffer concentration is about 40% to about 65% by weight in aqueous solution. The amount of ammonium lactate buffer added to the reaction mixture (based on the total weight of monomers added to the reaction mixture) is, for example, from about 1.0 to about 5.0 mole percent, such as from about 1.0 mole percent to About 3.0 mole percent, about 1.0 mole percent to about 2.0 mole percent, and the like.

  Some neutralizing agents such as ammonium lactate are useful for stopping the polymerization reaction in addition to neutralization. For example, it has been found that a CTFE polymer product having surprisingly superior thermal stability can be obtained by stopping the reaction using an ammonium lactate buffer and neutralizing the solution, compared with the case of neutralizing with another solution. . Thermogravimetric analysis at 300 ° C. (for details, see FIG. 7 below) shows that the polymer neutralized with ammonium lactate has improved thermal stability by about 25 to about 30%. Furthermore, the CTFE polymer product produced by the method of the present disclosure does not change color and does not generate bubbles during thermal processing such as film extrusion at a temperature of about 275 ° C. to about 325 ° C.

  An exemplary synthesis process for CTFE polymers according to this disclosure is described in the following paragraphs. In the first step of the synthesis of the CTFE-based polymer described herein, CTFE is subjected to a polymerization process in the presence of a solvent and an initiator, optionally with one or more additional monomers added.

  As used herein, the term “monomer” means a polymerizable alkene having at least one halogen atom, haloalkyl group, or haloalkoxy group bonded to the carbon atom of the double bond that undergoes polymerization. Refers to alkene optionally included. The term “polymer” means a polymer obtained by polymerization of one or more such monomers. Examples of monomers that can be used in addition to CTFE in the polymerization process of the present disclosure to form a copolymer of CTFE include, for example, vinylidene fluoride (VDF), 1, 2, as is well known in the art. -Difluoroethylene, vinylidene chloride (VDC), 1,1-dichlorodifluoroethylene, 1,2-dichlorodifluoroethylene, 1-chloro-1-fluoroethylene, tetrafluoroethylene (TFE), trifluoroethylene, vinyl fluoride, Hexafluoropropylene (HFP), hexafluoroisobutylene, perfluorobutylethylene (PFBE), pentafluoropropene, 3,3,3-trifluoro-1-propene, 2,3,3,3-tetrafluoropropene, 1, 3,3,3-tetrafluoropropene, fluorinated vinyl ethers Fluoromethyl vinyl ether (PMVE) or perfluoropropylene vinyl ether (PPVE), etc.), fluorinated allyl ether, fluorinated dioxoles; olefins (ethylene, propylene, isobutylene, etc.), and functionalized olefins (vinyl acetate, vinyl propionate, Allyl methacrylate, ethylene glycol dimethacrylate, trimethylolpropane triacrylate, maleic anhydride, itaconic acid, and the like), and combinations thereof. In a particular embodiment, the only monomer used in the polymerization process is CTFE and thus the resulting polymer is PCTFE.

  The terms “initiator”, “radical initiator” and “free radical initiator” refer to chemicals that can provide a source of free radicals either spontaneously or by exposure to heat or light. The terms “radical” and “free radical” refer to a chemical species having at least one unpaired electron. In the embodiments described herein, any commercially available radical initiator may be used. Suitable initiators include, for example: metal persulfates (such as sodium persulfate, potassium persulfate, and ammonium persulfate); organic peroxides or hydroperoxides (diacyl peroxides, ketone peroxides, peroxyesters, dialkyl peroxides, peroxyketals) , Peroxypivalates, peroxydicarbonates, transition metal carbonyls, etc.), and azo compounds (2,2′-azobisisobutyronitrile and its water-soluble analogues), and mixtures of any of the foregoing It is done.

Furthermore, any redox initiator system known to be useful in the preparation of fluorinated polymers such as PCTFE can be used in the embodiments described herein. Typical redox initiator systems include 1) organic or inorganic oxidizing agents, or mixtures thereof; and 2) organic or inorganic reducing agents, or mixtures thereof. Suitable oxidizing agents include metal persulfates (such as sodium persulfate, potassium persulfate, and ammonium persulfate); peroxides (hydrogen peroxide, potassium peroxide, ammonium peroxide, t-butyl hydroperoxide (TBHP). ), Cumene hydroperoxide, and t-amyl hydroperoxide), manganese triacetate, potassium permanganate, ascorbic acid, and mixtures thereof. Suitable reducing agents include sodium sulfites (such as sodium bisulfite, sodium sulfite, sodium pyrosulfite, sodium metabisulfite (MBS), and sodium thiosulfate); other sulfites (such as ammonium bisulfite), hydroxylamine Hydrazine, ferrous iron, organic acids (such as oxalic acid, malonic acid, and citric acid), and mixtures thereof. Redox initiator systems are the preferred initiators of the present invention. As a preferred redox initiator, potassium persulfate and an MBS reducing agent are used as oxidizing agents. In a more preferred embodiment, a redox initiator is used with a transition metal promoter. The accelerator can significantly reduce the polymerization time. Any commercially available transition metal can be used as a promoter. Preferred transition metals include copper, silver, titanium, ferrous iron (Fe ²⁺ ), and mixtures thereof. Ferrous iron is most preferred.

  Furthermore, examples of the radical initiator include persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate. The amount of persulfate added to the reaction mixture (based on the total weight of monomers added to the reaction mixture) can be, for example, from about 0.002 to about 1.0 weight percent. Alternatively, radical initiators can include organic peroxides (such as alkyl peroxides, dialkyl peroxides, or diacyl peroxides), and peroxyesters, or mixtures thereof. Exemplary dialkyl peroxides include di-tert-butyl peroxide (DTBP), dibenzoyl peroxide, or 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, into the reaction mixture. These addition amounts can be about 0.01 to about 5% by weight based on the total amount of monomers, more preferably about 0.05 to about 2.5% by weight based on the total amount of monomers. Exemplary peroxydicarbonate initiators are di-n-propylperoxydicarbonate, bis (tert-butylcyclohexyl) peroxydicarbonate, and diisopropylperoxydicarbonate, these additions to the reaction mixture The amount can be about 0.5 to about 2.5% by weight based on the total amount of monomers. Peroxyester initiators include tert-amyl peroxypivalate, tert-butyl peroxypivalate (TBPPi), and succinic peroxide. Transition metal carbonyls include decacarbonyl dimanganese. Alternatively, examples of the radical initiator include azo initiators such as 2,2'-azobis (2-methylpropionamidine) dihydrochloride.

  The polymerization reaction can be carried out in a suitable reaction vessel. The only requirement of the reaction vessel used to prepare the polymer of the present disclosure is that it can be pressurized and stirred. A conventional, commercially available sealable autoclave that can pressurize to the required reaction pressure (preferably above 3.36 MPa (500 psig) for safety reasons) is preferred. An autoclave inclined in the horizontal direction is preferred to an autoclave inclined in the vertical direction, but any arrangement may be used.

  The polymerization reaction is carried out in an aqueous reaction medium. In some embodiments, the reaction medium is deionized and nitrogen-substituted water. Generally, the same amount of water as about half the capacity of the reaction vessel is used. The selection of the polymer to water ratio is such that an aqueous dispersion with a polymer solids content of about 10% to about 70% is obtained. Water is poured into the autoclave in advance.

  As the polymerization reaction proceeds with time, a polymer emulsion is formed in the reaction medium, which can be further stabilized by using a surfactant. Exemplary surfactants include non-fluorinated hydrocarbon surfactants, siloxane surfactants, or mixtures thereof. For example, among the surfactants, sodium dodecyl sulfonate, sodium dodecyl benzene sulfonate (SDDBS), sodium octyl sulfonate, sodium lauryl sulfate, ammonium lauryl sulfate, and sodium laureth sulfate can be used with the monomer.

  If necessary, a chain transfer agent can be contained in the polymerization reaction medium to control the molecular weight of the polymer product. The chain transfer agent may be added all at once at the beginning of the polymerization reaction, or may be added continuously or stepwise during the reaction. The amount and form of addition of the chain transfer agent depends on the activity of the particular chain transfer agent used and the desired molecular weight of the polymer product. The amount of chain transfer agent added to the polymerization reaction is from about 0.05 to about 5 weight percent, for example from about 0.1 to about 2.0 weight percent, based on the total weight of comonomer added to the reaction mixture. Suitable chain transfer agents include oxygenates (alcohols, carbonates, ketones, esters, ethers, etc.), halocarbons, and hydrohalocarbons (chlorocarbons, etc.), and mixtures of any of these.

Paraffin wax or hydrocarbon oil can be added to the reaction medium as required. When paraffin wax or hydrocarbon oil is optionally added to the reaction, it functions as an antifouling agent, and the adhesion of the polymer to the reactor parts can be minimized or prevented. Any long chain saturated hydrocarbon wax or oil may be used to exert this function. An amount of oil or wax is added to the reactor that minimizes polymer adhesion to the reactor parts. The amount is generally proportional to the internal surface area of the reactor and can vary from about 0.5 to about 50 mg per cm ^{2 of the} internal surface area of the reactor.

  The monomer may be injected into the reaction vessel during polymerization either semi-continuously or continuously. “Semi-continuous” means that multiple batches of monomer are injected into the reactor during the polymerization reaction. The volume of the batch is determined by the desired operating pressure. The molar ratio of total monomer to radical initiator depends on the overall particle size and the desired molecular weight. The molar ratio of total monomers to initiator is preferably about 10 to about 10,000 moles, more preferably about 50 to about 1000 moles, and most preferably about 100 to about 500 moles per mole of initiator. is there.

  The radical initiator is generally added incrementally during the reaction. For the purposes of this disclosure, “initial injection” of initiator means that a large amount of initiator is added rapidly or in stages to cause initiation of polymerization. In the initial injection, the initiator is generally injected at about 10 ppm / min to about 1000 ppm / min for about 3 to about 30 minutes, either before, after, or during the monomer injection. “Continuous injection” means the slow addition of a small amount of initiator over a period of about 1 hour to about 10 hours until polymerization is complete. In continuous injection, the initiator is generally added at about 0.1 ppm / min to about 30 ppm / min.

  During the initiation of the polymerization reaction, the sealed reaction vessel and its contents are kept at the desired reaction temperature, or the temperature is varied during the reaction time according to the temperature profile. Controlling the reaction temperature is one determinant for establishing the final molecular weight of the polymer produced. In general, the polymerization temperature is inversely proportional to the product molecular weight. Usually, the reaction temperature is from about 0 ° C. to about 120 ° C., but temperatures above or below this range are also contemplated. The reaction temperature is preferably about 10 ° C to about 60 ° C. The pressure used for the polymerization can vary from about 170 kPa to about 5.5 MPa, but depends on the reactor capacity, the initiator system used, and the monomer selected. For example, in certain embodiments, the polymerization pressure is from about 300 kPa to about 4.2 MPa. It is known that increasing the pressure and temperature increases the reaction rate.

  The polymerization is preferably carried out with stirring to ensure proper mixing. Adjustment of the stirring rate during each polymerization may be necessary to avoid premature aggregation of the particles. The stirring speed and reaction time usually depend on the amount of polymer desired, but those skilled in the art can easily optimize the reaction conditions and obtain the desired results without undue experimentation. The stirring speed is generally in the range of about 5 to about 1000 rpm, preferably about 25 to 800 rpm, depending on the shape of the stirrer and the capacity of the vessel. The reaction time generally ranges from about 1 to about 24 hours, preferably from about 1 to about 12 hours. After completion of the reaction time, the CTFE polymer produced in the process of the present disclosure may be added by a usual method such as evaporation of an aqueous medium, freeze drying of an aqueous medium, or addition of a small amount of a flocculant or a coagulant (such as ammonium carbonate). Then, it can be isolated by filtration or centrifugation and drying.

  In one embodiment of the present disclosure, the synthesis process of the CTFE-based polymer can proceed according to the following steps. In a pressurized polymerization reactor equipped with a stirrer and a heating control device, a solvent (for example, deionized water), a co-solvent, if necessary, one or more monomers including at least CTFE, and an initiator are added. inject. Furthermore, you may mix | blend 1 or more types of surfactant, a chain transfer agent, and an antifouling agent to a mixture.

  Before introducing the monomer, the reactor is degassed to ensure an oxygen-free atmosphere for the polymerization reaction. The order of mixing the polymerization components can be changed. In one aspect, solvent, initiator, monomer, and optionally surfactant, antifouling agent, and / or chain transfer agent are injected into the reactor and the reactor is heated to the desired reaction temperature. Additional monomer is then fed into the reactor at a rate capable of maintaining a substantially constant pressure. Other variations of the polymerization process well known in the art are also conceivable. When the desired weight is fed to the reactor, the feed is stopped. If necessary, an additional radical initiator is added to complete the reaction in an appropriate time. As the monomer in the reactor is consumed, the reactor pressure decreases.

  Polymerization is carried out with stirring to ensure proper mixing. It is desirable to adjust the stirring speed during the polymerization to prevent premature aggregation of the particles. Agitation speed and reaction time usually depend on the desired amount of polymer product, but one skilled in the art can easily optimize reaction conditions without undue experimentation. The stirring speed is generally in the range of about 5 to about 800 rpm, such as about 25 to 700 rpm, depending on the shape of the stirrer and the capacity of the vessel. The reaction time is generally in the range of about 1 to about 30 hours, such as about 4 to about 20 hours.

  Additional agents that can be added to the reaction mixture at various points during the polymerization reaction process include neutralizers and quenchers. As used herein, the term “reaction terminator” refers to a compound that, when added to a reaction mixture, prevents further polymerization of unreacted monomers, ie, terminates the polymerization reaction. Thus, the polymerization reaction can be stopped using the reaction stop solution after the above reaction time has elapsed. By neutralizing the reaction medium as described above, it is possible to prevent the deterioration (discoloration, etc.) of the polymer product during the subsequent heat processing such as film extrusion.

In accordance with embodiments of the present disclosure, the reaction termination and solution neutralization steps may be performed using the same chemical (ie, a chemical having both reaction termination and solution neutralization characteristics). For example, the above-mentioned ammonium lactate buffer solution is added to the reaction mixture at the desired end of the polymerization reaction (this may be determined in advance), and the two functions of stopping the reaction and buffering and neutralizing the solution are exhibited. Can do. At this time, another neutralizing agent can be added instead of or in addition to the above-described neutralizing agent. An ammonium lactate solution or other neutralizing agent is added after the end of the reaction time (about 1 to about 24 hours from the start of the reaction, for example, about 1 to about 12 hours from the start of the reaction). The chemicals may be added in any suitable reaction pressures, e.g., from about 50 psi _g ~ about 150 psi _g (such as about 85 psi _g ~ about 135 psi _g).

  Subsequently, an exemplary embodiment using an ammonium lactate solution as a neutralizing agent will be described. By adding an ammonium lactate solution as a neutralizing agent to the reaction medium, there is an advantage that further polymerization of unreacted monomers is prevented, and as a result, the polymerization reaction is stopped. The addition of the ammonium lactate solution also brings the pH of the reaction mixture closer to neutrality, thereby reducing the degradation of the polymer during thermal processing. For example, when the polymerization reaction proceeds during the reaction time, the pH is about 1.5 to about 2.5 (such as about 2.0). As is known in the art, the nominal pH of ammonium lactate is about 4.8 when used in about 65% by weight aqueous solution. The reaction medium is neutralized by the addition of the ammonium lactate solution, and the pH is from acidic to near neutral (for example, about 1.8 to about 6.0, specifically 1.8 to 5.0, more preferably About 3.0 to about 5.0, most preferably about 4.0 to about 5.0). In some embodiments, no other buffer may be used during the polymerization reaction and prior to the introduction of the ammonium lactate solution.

  After the ammonium lactate solution is added and the polymerization reaction is completed, the reactor is returned to room temperature, and the remaining unreacted components are released to atmospheric pressure. In some embodiments, a “heating / cooling” process is used. In that case, after stopping the reaction, the reactor temperature is temporarily increased (for example, about 50 ° C. to about 60 ° C. (eg, 55 ° C.)) and then cooled to about 30 ° C. to 40 ° C. (eg, 35 ° C.). The heating / cooling procedure can be performed for about 30 minutes to about 2 hours (eg, about 1 hour). The reaction medium containing the polymer product is then recovered from the reactor. The recovered product includes a stable mixture of reaction components (ie, solvent, initiator (and / or initiator degradation)), and solid polymer product. The mixture containing the product polymer is filtered, washed with deionized water, and then dried to a constant weight to obtain a solid polymer composition. Alternatively, the mixture containing the polymer product is filtered to remove the solvent and the resulting crude product is dissolved in an organic solvent and then precipitated using a different solvent. The precipitate is dried to a constant weight to obtain a solid polymer composition.

  In a particular embodiment, the polymer product obtained as a result of the polymerization reaction described above is PCTFE or CTFE and the following monomers (vinylidene fluoride, 1,2-difluoroethylene, vinylidene chloride (VDC), 1,1 -Dichlorodifluoroethylene, 1,2-dichlorodifluoroethylene, 1-chloro-1-fluoroethylene, tetrafluoroethylene, trifluoroethylene, vinyl fluoride, hexafluoropropylene (HFP), hexafluoroisobutylene, perfluorobutylethylene, penta Fluoropropene, 3,3,3-trifluoro-1-propene, 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene, fluorinated vinyl ethers (perfluoromethyl vinyl ether, or Perfluoropropylene vinyl Ethers), fluorinated allyl ethers, fluorinated dioxoles; olefins (ethylene, propylene, isobutylene, etc.), and functionalized olefins (vinyl acetate, vinyl propionate, allyl methacrylate, ethylene glycol dimethacrylate, Methylolpropane triacrylate, etc.), maleic anhydride, itaconic acid, or combinations thereof, which are known in the art). This polymer product has surprisingly improved thermal stability and melt extrusion, pelletization, thermoforming, particularly at temperatures of about 275 ° C. to about 325 ° C. (such as about 300 ° C.). , With respect to lamination).

  The polymer product obtained in the present disclosure can be used for various commercial applications. Applications include barrier films for pharmaceutical packaging and medical packaging, lining materials for chemical processing equipment, gas separation membranes, wire insulation materials, cable sheathing materials, hoses, tubes, sealing materials, gaskets, O-rings, textiles Examples thereof include a dispersion for processing. Various thermal processing techniques that can be suitably used in making the aforementioned commercial products are well known to those skilled in the art.

Examples The present disclosure is illustrated by the following non-limiting examples. It should be noted that various changes and modifications can be made to the following examples and processes without departing from the scope of the present invention (as defined in the appended claims). Accordingly, it should be understood that the following examples are to be construed as merely illustrative and not a limitation of the present invention.

In the first example, a PCTFE polymer was produced using conventional processing techniques. The CTFE monomer 5 kg, deionized water as a solvent, and with potassium persulfate and iron as an initiator, 37.7 ° C., was charged 30 gallon reactor vessel pressure 122psi _g. The reaction was allowed to proceed for about 8 hours. About 1 hour after the start of the reaction, 10 kg of CTFE was further added, and about 3.5 hours after the start of the reaction, further 10 kg of CTFE was added (the total amount of CTFE was 25 kg). The pH of the reaction mixture was kept at about 2.0 throughout the reaction process. No reaction terminator or buffer / neutralizer was used. FIG. 1 shows the temperature and pressure in the reaction vessel during the polymerization reaction process. The pressure in the reaction vessel as shown, dropped to 90 psi _g at the end of the reaction process.

In a second embodiment, except that the polymerization was terminated reaction using 65 wt% ammonium lactate aqueous solution 500mL at a pressure of 131Psi _g, using essentially the same processing technique as that described in the first embodiment PCTFE polymer was produced. FIG. 2 shows the temperature and pressure in the reaction vessel during the polymerization reaction process. The addition of the ammonium lactate solution stopped the polymerization reaction, and the pH of the reaction mixture rose to about 3.7.

In a third embodiment, except that the polymerization was terminated reaction using 65 wt% ammonium lactate aqueous solution 600mL at a pressure of 131Psi _g, using essentially the same processing technique as that described in the first embodiment PCTFE polymer was produced. FIG. 3 shows the temperature and pressure in the reaction vessel during the polymerization reaction process. The addition of the ammonium lactate solution stopped the polymerization reaction, and the pH of the reaction mixture rose to about 4.5.

In a fourth embodiment, except that it stopped at a pressure of 90 psi _g polymerization reaction using 65 wt% ammonium lactate aqueous solution 600 mL (after descent), those substantially the same as described in the first embodiment PCTFE polymer was prepared using processing techniques. FIG. 4 shows the temperature and pressure in the reaction vessel during the polymerization reaction process. The addition of the ammonium lactate solution stopped the polymerization reaction, and the pH of the reaction mixture rose to about 4.5.

In a fifth embodiment, except that it stopped at a pressure of 90 psi _g polymerization reaction using 65 wt% ammonium lactate aqueous solution 600 mL (after descent), those substantially the same as described in the first embodiment PCTFE polymer was prepared using processing techniques. In addition, a “heat / cool” process was used, and after the pressure drop process, the temperature was increased to about 55 ° C. and then decreased to about 35 ° C. FIG. 5 shows the temperature and pressure in the reaction vessel during the polymerization reaction process. The addition of the ammonium lactate solution stopped the polymerization reaction, and the pH of the reaction mixture rose to about 4.5.

In a sixth embodiment, except that the polymerization was terminated reaction using 65 wt% ammonium lactate aqueous solution 600mL at a pressure of 131Psi _g, using essentially the same processing technique as that described in the first embodiment PCTFE polymer was produced. In addition, a “heat / cool” process was used, and after the pressure drop process, the temperature was increased to about 55 ° C. and then decreased to about 35 ° C. FIG. 6 shows the temperature and pressure in the reaction vessel during the polymerization reaction process. The addition of the ammonium lactate solution stopped the polymerization reaction, and the pH of the reaction mixture rose to about 4.5.

  FIG. 7 shows the results of thermogravimetric analysis (TGA) of Example 1 of the prior art in comparison with Examples 2 to 6 according to the present disclosure. TGA was performed at a temperature of 300 ° C. The polymer of Example 1 of the prior art had an average weight loss after 41 minutes of 1.06%. In contrast, the polymers of Examples 2-6 of the present disclosure had an average weight loss after 41 minutes of 0.70 to 0.79%. Therefore, it can be seen that the embodiment of the present disclosure has significantly less heat deterioration with time than the embodiment according to the prior art.

In the seventh example, a PCTFE polymer was produced using conventional processing techniques. The CTFE monomer 0.6 kg, deionized water as a solvent, and 37.7 ° C. with potassium persulfate and iron as an initiator, were charged in three gallon reactor vessel pressure 127psi _g. The reaction was allowed to proceed for about 5 hours. About 1 hour after the start of the reaction, an additional 2.17 kg of CTFE was added (the total amount of CTFE was 2.77 kg). The pH of the reaction mixture was kept at about 1.8 throughout the reaction process. 3 hours after the addition of sodium metabisulfite to the reactor (MBS), and stops at a pressure 90 psi _g. The excess pressure was then relieved for 1 hour before adding 250 mL of 25 wt% lithium citrate solution to the reaction mixture twice and stirring at 29.3 ° C. for 30 minutes. FIG. 8 shows the temperature and pressure in the reaction vessel during the polymerization reaction process. The addition of the lithium citrate solution stopped the polymerization reaction, and the pH of the reaction mixture rose to about 5.1.

In the eighth example, a PCTFE polymer was produced using conventional processing techniques. The CTFE monomer 6 kg, deionized water as a solvent, and with potassium persulfate and iron as an initiator, 37.7 ° C., was charged 30 gallon reactor vessel pressure 127psi _g. The reaction was allowed to proceed for about 9 hours. About 1 hour after the start of the reaction, 10 kg of CTFE was further added, and about 3.5 hours after the start of the reaction, further 10 kg of CTFE was added (the total amount of CTFE was 26 kg). The pH of the reaction mixture was maintained at about 2.1 throughout the reaction process. The addition of sodium metabisulfite to the reactor (MBS), after 8 hours, and stopped at a pressure 90 psi _g. The excess pressure was then released over 0.5 hours, after which the reaction mixture was divided into 8 equal parts. Next, the first portion was neutralized with 320 mL of 20 wt% ammonium citrate solution and stirred at room temperature and normal pressure for 3 hours. The polymerization reaction was stopped by the addition of ammonium citrate solution, and the pH of the reaction mixture rose to about 4.94.

In the ninth embodiment, by stopping the addition of the MBS solution into the reactor after 6 hours, except that the polymerization reaction was stopped at a pressure of 90 psi _g, processing technology substantially as described above in the first embodiment PCTFE polymer was prepared using the same processing technique. An aqueous solution (13.2 wt%) of 72.14 _g sodium hydroxide dissolved in 476.2 _g deionized water was then added to the reaction mixture at 37.5 ° C. and pressure 89.8 psig and stirred for 10 minutes. Degassed. FIG. 9 shows the temperature and pressure in the reaction vessel during the polymerization reaction process.

  Thus, although the embodiments of the improved PCTFE homopolymer and copolymer have been described, these polymers are suitable for the production of articles processed at high temperatures and suitable for the structure of shaped members. Can be used. The embodiment also describes methods for producing thermally stable and less acidic PCTFE homopolymers and copolymers, which are related to machinability (especially with respect to melt extrusion, pelletization, thermoforming, and lamination). ) Is improved.

In the foregoing detailed description of the invention, only one or more exemplary aspects have been described, but it will be appreciated that many variations may exist. It will be appreciated that the exemplary embodiments are merely examples of the invention and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description provides convenient guidance for those skilled in the art to practice the exemplary embodiments of the present invention, and does not depart from the scope of the appended claims and their legal equivalents. It should be understood that various modifications may be made by those skilled in the art to the function and arrangement of the elements described in the exemplary embodiments.
[1] After reacting one or more monomers containing CTFE in a reaction medium having a pH of about 1.5 to about 2.5 in the presence of an initiator, and after a predetermined polymerization reaction time has elapsed, A method of synthesizing a chlorotrifluoroethylene (CTFE) -based polymer, comprising adding a neutralizing agent to the reaction medium to raise the pH of the reaction medium within a range of about 1.8 to about 6.0.
[2] The addition of the neutralizing agent includes adding an aqueous base or a buffer, and includes adding the neutralizing agent after the polymerization reaction time has elapsed from about 1 hour to about 24 hours. The method described.
[3] The method according to [2], comprising adding a neutralizing agent after a polymerization reaction time of about 1 hour to about 12 hours has elapsed.
[4] The addition of the neutralizing agent includes adding a buffer solution having a pH of about 3.0 to about 7.0 after a predetermined polymerization reaction time has elapsed, and the addition of the buffer solution is an acetate solution. Adding an aqueous solution selected from the group consisting of: a citrate solution, a phosphate solution, and a lactate solution, and mixtures thereof after a predetermined polymerization reaction time has elapsed. the method of.
[5] The addition of the buffer includes adding an aqueous solution selected from the group consisting of an ammonium lactate solution, a sodium lactate solution, a potassium lactate solution, and a mixture thereof after a predetermined polymerization time has elapsed. Further, the addition of the buffer solution includes adding an aqueous ammonium lactate solution after a predetermined polymerization time has elapsed, and the addition of the buffer solution further comprises adding an ammonium lactate concentration of about 5 to about 75% by weight of the total solution weight. The method according to [4], comprising adding an aqueous ammonium lactate solution.
[6] The method according to [5], wherein the addition of the buffer solution includes adding an aqueous ammonium lactate solution having an ammonium lactate concentration of about 40 to about 65% by weight of the total solution weight.
[7] The addition of the ammonium lactate solution includes adding about 1.0 to about 5.0 mol% ammonium lactate with respect to one or more monomers, and the addition of the ammonium lactate solution further includes: The method according to [5], comprising adding about 1.0 to about 2.0 mol% ammonium lactate to one or more monomers.
[8] The reaction of one or more monomers including CTFE is carried out by converting one or more monomers including CTFE into vinylidene fluoride, 1,2-difluoroethylene, vinylidene chloride, 1,1-dichlorodifluoroethylene, 1 , 2-dichlorodifluoroethylene, 1-chloro-1-fluoroethylene, tetrafluoroethylene, trifluoroethylene, vinyl fluoride, hexafluoropropylene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, 3,3,3- Trifluoro-1-propene, 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene, fluorinated vinyl ethers (such as perfluoromethyl vinyl ether or perfluoropropylene vinyl ether), fluorinated allyl ether , Fluorinated dioxoles; olefins (ethylene, propylene, isobutylene, etc.), and functionalized olefins (vinyl acetate, vinyl propionate, allyl methacrylate, ethylene glycol dimethacrylate, trimethylolpropane triacrylate, etc.), anhydrous The method according to [1], comprising reacting with one or more monomers selected from the group consisting of maleic acid, itaconic acid, and combinations thereof.
[9] the addition of the neutralizing agent comprises adding a neutralizing agent in reaction pressure of about 50 psi _g ~ about 150 psi _g, further comprises performing a heating / cooling steps after neutralizing agent addition, [1 ] Method.
[10] The method according to [1], further comprising filtering and drying the CTFE polymer product after adding the neutralizing agent, and further heat-treating the CTFE polymer product after filtration and drying. Method.

Claims (3)

Reacting one or more monomers containing CTFE in a reaction medium having a pH of 1.5 to 2.5 in the presence of an initiator, and after a predetermined polymerization reaction time has elapsed, a neutralizing agent is added to the reaction medium. Adding to raise the pH of the reaction medium within the range of 1.8 to 6.0,
A method for synthesizing a chlorotrifluoroethylene (CTFE) -based polymer. Reacting one or more monomers comprising CTFE in a reaction medium having a pH of 1.5 to 2.5 in the presence of an initiator;
After the polymerization reaction time of 1 to 24 hours has elapsed, a neutralizing agent containing a buffer solution containing an aqueous ammonium lactate solution is added to the reaction medium to raise the pH of the reaction medium to a range of 1.8 to 6.0. Here, the aqueous ammonium lactate solution contains 5 to 75% by weight of ammonium lactate based on the total solution weight, and the addition of the ammonium lactate solution is 1.0 to 5 with respect to the one or more monomers. Filtering and drying the CTFE polymer product after adding 0.0 mol% ammonium lactate and after adding the neutralizing agent;
A method for synthesizing a chlorotrifluoroethylene (CTFE) -based polymer. Reacting one or more monomers comprising CTFE in a reaction medium having a pH of 1.5 to 2.5 in the presence of an initiator;
After the polymerization reaction time of 1 to 12 hours has elapsed, a neutralizing agent containing a buffer solution containing an aqueous ammonium lactate solution is added to the reaction medium to raise the pH of the reaction medium to a range of 1.8 to 5.0. Wherein the aqueous ammonium lactate solution contains 40-65% by weight ammonium lactate of the total solution weight, and the addition of the ammonium lactate solution is 1.0-2 with respect to the one or more monomers. Adding 0 mol% ammonium lactate,
Filtering and drying the CTFE polymer product after adding the neutralizing agent, and filtering and drying the CTFE polymer product, and then cooling the CTFE polymer product to a temperature of 275 ° C. to 325 ° C. Heat processing with,
A process for producing a chlorotrifluoroethylene (CTFE) -based polymer product.

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